Pneumatic drop hammer



Oct. 7, 1952 FlTZGERALD 2,612,868

PNEUMATIC DROP HAMMER Filed March 5, 1948 5 Sheets-Sheet 1 Fig.1. Ia I5 I 9 9 1 Ln-Mr: 57

H a7 /4 ea I 44 99 o o I l I0 93 86 f 94 96 1 5 laa H i. ll 4 i 10 10 Oct. 7, 1952 R. P. FITZGERALD 2,612,868

PNEUMATIC DROP HAMMER Filed March 5, 1948 3 Sheets-Sheet 5 Patented Oct. 7, 1952 PNEUMATIC DROP HAMMER Reginald P. Fitzgerald, Braintree, Mass., assignor to Pneumatic Drop Hammer Company, Braintree, Mass., a corporation of Massachusetts Application March 3, 1948, Serial No. 12,707

ject of the invention is to provide a pneumatic drop hammer of economical construction in which the operation of the hammer is controlled by a single valve having manually operable means for controlling the force of the blow of the hammer.

More specifically the object of the invention is to provide a pneumatic drop hammer having a lifting cylinder and piston connected to the hammer with means for supplying air under pressure to the lifting cylinder and manually operated means for so regulating the escape of air from the cylinder to permit the hammer to drop at a controllable speed andthereby to adjust the force of impact of each blow.

A'further object of the invention is to provide manually operable means for so adjusting the controlling means as to cause the hammer to strike successive blows of the hammer with the same force of impact.

Another object of the invention is to provide a pneumatic drop hammer construction of the character described with means for automatically preventing any possibility of the hammer striking an undesirable repeat blow.

A further object of the invention is to provide a'novel mechanism for cushioning and arresting the upward movement of the hammer.

" 'Another important object of the invention is to provide manually operable means for actuating the controlling means which will prevent undesirable shock or injury to the operator.

Another object of the invention is to provide a standard for a drop hammer so constructed as to enable the operator to sit while operating the hammer in a position directly facing the hammer-and anvil thereby facilitating feeding blanks to the anvil and more easily and conveniently controlling the operation of the hammer.

Another object of the invention is to provide a drop hammer construction having a single rotatable operating valve with an axially alined control rod connected thereto by a universal joint thereby to prevent binding or wear of the valve in its bearing.

These and other objects and features of the invention will appear more fully from the following description and the accompanying drawings and will be particularly pointed out in the claims.

A preferred embodiment of the invention is 11- lustrated in the accompanying drawings, in which,

Fig. 1 is a front view of the drop hammer;

10. Claims. (Cl. 121-30) Fig 2. is an enlarged detatil view, partially in vertical section, illustrating the control valve and the mechanism for actuating the same; 1

Fig. 3 is a detail horizontal sectional view on line 33,Fig 2; J

Fig. 4 is a detail horizontal sectional view'on line 4--4, Fig.2;

Fig. 5 is a horizontal sectional view on line, 5+5, Fig. 2;

Fig. 6 is a detail horizontal sectional view on line 6-6, Fig. 2; p

Fig. '7- is an exploded detail view of the mechanisms for mounting the lower end of the control rod and the means for adjusting the same so to limit the rotative movement of the valve as to restrict the rate of escape of air from the cylinder to produce a blow of the hammer of predetermined force; I

Fig. 8 is a detail view mainly in vertical section of the lower portion of the lifting cylinder, the piston and piston rod therein, and the bufler construction for cushioning and arresting-the upward movement of the hammer Fig. 9 is an exploded view illustrating the universal connection between the valve stemand the valve operating rod shown in Fig. 2; and, h

Fig. 10 is a horizontal sectional view of the base of the hammer on line Ill-l0, Fig 1.

The drop hammer shown in theacoompanying drawings comprises an integral cast metal base in the form of a pedestal having a rectangular bottom section I, an intermediate section 2 of upwardly converging cruciform cross section having vertical ribs 3 extending at right angles to each other and a rectangular flat upper section 4 of suitable area and thickness forming an anvil upon which is mounted the usual die shoe 5' and the superstructure of the hammer and the operating mechanisms therefor.

This pedestal construction is adapted to permit the legs of an operator, when seated, to straddle the forwardly extending rib and thus comfortably to face the operating parts of the machine and the controlling mechanisms therefor and conveniently to place blanks upon the die and to operate the controlling mechanism. f

The means for supporting and actuating the hammer include a frame which isv mounted upon the anvil having vertical preferably cylindrical columns 6 and 1 forming guides for a hammer 8. The upper ends of the columns 6 and 1 extend through and are mounted in anoverhead beam 9 and base members H), which connect'the beam 9 to the anvil, are located rearwardly'of the columns 6 and 1 respectively.

end of which is secured to the hammer 8. A

collar 5, which is fixedly secured to the cylinder I2 and is bolted to the upper face of the beam,

has an internal rabbet in its lower face which.

encloses the periphery of a rigid annular plate I6 which forms a common head for the lifting cylinder l2 and the cylinder I of the buffer and has an upwardly extending circular wall l1 surrounding and narrowly spaced from the piston rod to permit air under pressure to pass from the lifting cylinder l2 into the buffer cylinder Preferably a reinforcing washer I8 which surrounds the wall I! extends into the rabbet and is clamped therein by the collar l5.

The cylindrical aperture H. which forms the cylinder of a buffer for cusl ming and arresting the upward movement of the hammer, is provided with a piston l9 having an annular gasket of U-shaped cross section secured to itsupper face, engages the piston rod and the cylinder wall. The piston l9 has an integral downwardly extending tubular sleeve 2| slidably fitting the piston rod l4 and extending through the lower head of the buffer cylinder II which, as shown, is a heavy metal plate 22 which is secured to the lower face of the beam 9. However, it will be understood that the lower head of the bufier cylinder may be an integral web of the beam if the cylindrical aperture and-a central opening therein is bored downwardly into but not completely through the beam 9. Suitably controlled means are provided for supplying air under pressure to the lifting and buffer cylinders to raise the hammerand to cushion and arrest the upward movement thereof. In the preferred embodiment of the invention shown herein the overhead beam is provided with a longitudinal bore 23 forming'a conduit having an upwardly extending section 24 communicating with an L-shaped bore 25 in the collar I5 to communicate with an alined aperture in the cylinder sufliciently near the lower end thereof to enable air under pressure when exhausted from the cylinder to discharge any lubricating oil which accumulates upon the plate I6 between its upwardly extending central wall I 1 and the wall of the cylinder.

The piston rod M has adjustably secured to it a collar 26 adapted to be so positioned as properly to engage the sleeve 2| when the hammer approaches the upward limit of its movement thereby raising the piston l9 against the force of the-air under pressure supplied to the lifting .and buffer cylinders thereby to cushion and arrest the movement of the piston. Upon exhaust of air from the lifting cylinder the buffer piston and its sleeve 2| will. descend until the piston rests upon the lower head 22 of the buffer cylinder.

One of the important objects of the invention is to provide means for so controllably regulating the exhaust of air from the cylinder as to cause the hammer to strike a blow of maximum force, or a blow of predetermined force less than th maximum, or selectively to strike a plurality of blows of uniform predeterminedforce.

In the present construction the conduit 23 in the overhead beam communicates at its end remote from the cylinder with the atmosphere or with a suitable mufller 21 as shown in Fig. 1 and a single operating valve in the conduit 23 controls the admission of air to the lifting and buffer cylinders and the rate of exhaust of air from the lifting cylinder, and manually operable means are provided for so positioning the valve as to enable the hammer to strike a maximum blow or so restricting the escape of air from the cylinder as to cause the hammer to strike a blow of any desirable force less than said maximum.

As illustrated in the drawings the overhead beam is provided in suitable proximity to the exhaust end of the conduit 23 with a vertical cylindrical bore 28 axially crossing the conduit 23 and lined with a cylindrical bushing 23 having diametrically alined ports 30 and 3| coinciding with the conduit 23. The bore 28 is provided at its upper end with a screw threaded wall and a nut 32 which is mounted thereon engages the upper end of the bushing 29. Desirably the nut 32 is provided with a central duct and cavity through which oil may be supplied to the valve with a suitable removable plug closing the duct.

The bore 28 is also provided at its lower end with a screw threaded wall which is engaged by a tubular nut 33 having an integral downwardly projecting extension 34 fitting the cylindrical stem 35 of a cylindrical valve 36 which is rotatably mounted in the bushing 29. The upper face of the nut 33 is provided with an annular countersink containing an antifriction member or packing 31 which surrounds the valve stem 35 and engages the lower face of the valve 36.

The valve 36 is shown in Fig. 6 as a rotatable valve having ports adapted selectively to be p0- sitioned to admit air under pressure to the lifting cylinder or to permit controlled exhaust of air from the cylinder. The beam 9 is provided with an inlet passage 38 through which air under pressure is supplied to the valve 36 and thence selectively to proper ports therein to the lifting cylinder to raise the hammer, or through ports in the valve to permit the regulated escape of air from the cylinder. The preferred operating valve 36 has an integral cylindrical head 39 having a diametrical bore 40 therethrough preferably of the same diameter as that of the conduit 23 and provided at its ends with ports 4| and 42 adapted to communicate with the conduit 23 and a radial bore 43 extending at right angles to and communicating with the bore 40, thereby being so positioned that when the valve body is rotated in one, preferably a clockwise direction the valve port 4| will register with the inlet passage 38 and the port 43 with the conduit 23 to admit air under pressure to the lifting cylinder thereby to raise the hammer.

When the valve is rotated in the opposite direction the ports 4| and 42 will both communicate with the conduit 23 to permit escape of air from the liftin cylinder. Manually operable means are provided for rotating the valve in the opposite, counterclockwise, direction so to position the valves 4| in axial alinement with the conduit 23 to permit such rapid exhaust of air from the cylinder as to permit the hammer to drop under the influence of gravity and strike a maximum blow, or selectively to rotate the valve such desired lesser distance that the ports 4| and 42 respectively will be so adjustably positioned as to restrict the rate of exhaust of air from the cylinder to cause a back pressure, of the air in the plying air under pressure shown.

acting upon the hammer adaptedscontrollably to cause. the hammer to strike a: blow of. any desired force less than said maximum.

Means are provided. in the present invention for: adjustably limitingithe rotative movement of the valves 'inwsuch manner that repeated blows of the hammer may be struck with uniform force.

Any suitable; means may be provided forsupt the inlet port 38 in the overhead beam. In the present construction an elbow fitting M, such as is usual in the art, is secured to the beam in communication with the inlet port 38 therein and is connected by. a preferably'flexible pipe to a fitting 46 having a shut-off valve 41 in a conduit 48 leading from an air'compressor'of the usual type,. not

Desirably the flexible pipe 45- is attached to and extends along one-of the braces l0 but for clarity of. illustration is shown as extending upwardly' from the lower fitting 45 to the fitting 41! parallel. to the columns I.

- In order to insure accuracy of rotation of the valve 36 and to prevent wear, the valve stem 35 is securedto a'vertical "actuating rod '49 of a novel universal joint, which is illustrated in Figs.

'2 and 9, in which the lower end of the valve stem 35 is; provided with a diametrical flat tongue 50 j which engages a diametrical groove 5| in a cylindri'cal member 52 having in its under face a groove 53 extending at right angles to the groove 5|. The control rod 49 has at its upper end a tongue 54 adapted to engage the groove 53' (Fig.

A sleeve 55, which is secured to the upper end of the control rod by a bolt 56, surrounds the cylindrical member 52 of the universal joint and the adjoining cylindrical portion 34 of the lower nut 33, thereby preventing lateral displacement of the interengaging members of the universal joint which are held in engagement by the upper and lower bearings of the valve and the controller rod.

' The lower end of the valve actuating rod 49 extends axially into a cylindrical socket 58 in the anvil top' land desirably is provided at its end with a conical bearing 59 as shown in Fig. '7. The rod 49' has in proximity to the conical end an angular, preferably square, portion 60 adapted to be engaged by downwardlyextending. mem- "bers' having shoulders adapted to cooperate with stop pins one of which is adjustable to limit the rotation of the valve 36 as hereinafter described.

A cylindrical bearing'blocl; 6| is mounted in the base or the socket 58 and is adapted to be ad- .justabl'y secured therein by a set screw 62. It is.

provided with a central conical socket 63 to re- "carve the conical end 59 of the control rod. A

collar 54 having an angular preferably rectangular hole 55 therethrough which fits the rectangular portion 50 of the control rodis mounted. upon the upper face of the bearin block 6| and is provided with laterally extending shoulders 65 and 6? as shown in Fig. '7, the shoulder 66 being 1 adapted to engage a stop pin 68 extending upwardly from the bearing block 6| as shownin Figs-2; land 7. When the valve rod 49 is rotated in a clockwise direction until the shoulder f 56 engages the stop pin 68 the port of the valve 66 will communicate with the inlet passage 38 in vthe beam 9 and the port 43 will communicate with the conduit 23, thereby to supply air under pressure to thelifting cylinder to raise thehammer.

Suitable means areprovided for-controlling-the,

adapted to be engaged by the shoulderlil. of the socket to limitthe rotationof the control rod andthe valve 36- in acounterclockwise direction. The: hub :69 is provided with a laterally extending-handle l2 by means of which it may be rotated and. is provided therebeneath-with an-annular groove 13 in which the 'arcuate end of a clamping plate 14 is seated and which is adapted to be moved to clamping: position by a screw 15 having a handle 16 vas shown in Figs 3 and'l. The hub 69 isprovided' with a scale having graduationsll adapted to be positioned in registry'w ith an index which, as shown in Figs; 2 and'-3', comprises a vertical stud l8 -which is mounted in and: extends. upwardly from the anvil 4' in radial alinement with the-stud 68 which projects upwardly from the bearing block 6 By reason of this construction when the valve operating rod is'rotatedv in. a clockwise. direction to cause the shoulder-66 of the collar-*Mto engage the stationary pin 68, the port 4| of the valve will register: with the. inlet port 38 in the overheadbeam' and'the port 43 of the valve will register with the conduit'23- thereby'permitting air under pressure to enterthelifting cylinder with full force toqraiseithe piston. By rotative adjustment of. the hub in a. clockwise direction. the downwardly extending stop pin 'H' ofthe hub|i9v maybe so positioned that" theflarea: of the exhaust" ports 41; and. 42. of the valve. 36 will be positioned so toxrestrictthe escape of. air from-the'cylinder'asto adjust therate of descent of the hammer to stri-ke a blow of predetermined force; The positioning. of the exhaust ports-of the valve 'maybe accurately determined. by'the position of the scale onthe hub iwith respect to the index l8 and the hub fixedly clamped in the desired position. to: cause the hammer' to strike=:repeated blows :with the same predetermined iforcen .Desirably means areprovidedto rotate. the control.rod'automatically' in a clockwise direci-i tion approximately at the time the hammer strikes. itsblow and: thereby to prevent arebounding blow of the hammer. This is accomplished by usual .mechanism comprising. a. sleevef'19 adjustably mounted upon the controlrodl above andinproximityto the plane of. impact: of. the hammer .upon the anvil. and. provided iwithaa spiral cam adapted to be-engaged'by andprojected upon' the hammer just in advance of. the

duit 23 in such manner as to permit the hammer to drop with full; forceyor to, restrict-the escape of air from the cylinder. in such man.- ner as to control the rate ofdescentof the ham mer and-the. force of. the-blow, and whiehwill .(Figs. 2 and 5) a sleeve 8| is fixedly secured to the control rod 49 at a convenient distance above :its base by a pin 82 extending therethrough.

The sleeve 8| is provided with a flat face 83 adapted to be engaged by the fiat head 84 of a cylindrical plunger 85 which is slidably mounted in a handle 88 and is forced into engagement with the sleeve by a spring 81 in the handle engaging a cylindrical abutment 88 secured within the handle by a. screw threaded plug 89 (Fig. 5). The handle 88 has at its end adjacent the control rod a laterally ofiset arm 98 having a horizontal end portion 9| which is rotatably mounted upon the control rod 49 and secured in position thereupon by a collar 92 engaging the upper face of the arm 9|. When, therefore, the control rod is automatically rotated in a clockwise direction upon descent of the hammer the rotation of the sleeve 8| will force the plunger 85 gently out of engagement with the flat face 83' of the collar 8|, thus avoiding a shock to the hand of the operator.

Another feature of the drop hammer construction is to provide safety means for preventing improper or unintentional descent of the hammer which might injure the operator or damage the hammer or anvil dies or the blank if therebetween by reason of release or reduction in air pressure in the lifting cylinder caused either by inadvertent operation of the exhaust mechanism or by leakage of air from the lifting cylinder. This is accomplished by providing means for latching the hammer at substantially the upper limit of its movement and also providing a supplemental abutment for-preventing the hammer die from striking the anvil die both of which must bemanually removed from the path of the hammer by the left hand of the operator before and while the valve controlling rod 49 is operated by the operators right hand to rotate the valve 38-to exhaust position to permit the'hammer to drop. By thus requiring the operator to use both hands after the blankhas been placed on the anvil to release and to control the hammer such injuries are impossible. i The mechanism shown in the drawings for preventing such uncontrollable descent of the hammer comprises an abutment rod 93 normally located in the path of the hammer with the lower end of the rod resting upon the fiat face of the anvil 4 and its upper end extending above the plane of impact of the hammer and anvil dies. The rod 93 is fixedly secured in a sleeve 94 on the end of an arm '95 extending from a collar 98 which is secured upon a vertical rod 91 which is journaled at its lower end in a suitable bearing in the anvil 4 and is journaled at its upper end in the overhead beam 9 in proximity to and forwardly of the hammer guiding column 8; In order to support the hammer at the upper limit of its movement the rod 91 has fixedly and adjustably secured to it a latch 98 extending in substantial parallelism with the arm 95 of the lower abutment. The latch 98 and the abutment rod 93 are normally held in the path of the hammer by a spiral torsional spring 99 which encircles the upper end portion of the rod 91 and is anchored at its upper end to the overhead beam 9 and at its lower end to a collar which is fixedly secured to the rod 91. The collar 98 is provided with a handle I08 adapted to be grasped by the left hand of the operator and moved in a clockwise direction to swing the latch 98 and the abutment rod 93 out of the path of the hammer.

In starting the operation of the machine, assuming that the hammer is in raised position with its lower face resting upon the latch 98 and the work placed upon the anvil die, the operator will first grasp the handle 88 with his right hand and rotate it in a clockwise direction thereby positioning the valve ports 4| and 43 respectively in communication with the inlet port 38 and the conduit 23 to supply air under pressure to the lifting cylinder, thereby raising the hammer to the upper limit of its movement and removing the pressure of the hammer upon the latch 98. He will then grasp the handle I08 and rotate the rod 91 in a clockwise direction sumciently to remove the latch 98 and the abutment rod 93 from the path of the hammer and continue to withhold the latch and abutment out of the path of the hammer. The operator will then rotate the handle 88 of the control rod 49 in a counterclockwise direction to position the ports 4| and 42 in communication with the conduit 28 and if a full blow is to be struck will retain the ports in full registry with the conduit 23. If the operator desires to strike a lesser blow the handle 88 will be rotated such lesser distance as will restrict the rate of exhaust air from the lifting cylinder to such an extent as may be required to strike a blow of predetermined force.

If the operator desires to strike a series of repeated blows of less than full force he will, preparatory to the removal of the latch and abutment from the path of the hammer, grasp the handle 12 of the hub 89 and rotate the hub in a clockwise direction to a position indicated by the registry of a desired graduation of the scale 88 on the hub with the index 18 which extends upwardly from the anvil 4 and will lock the hub in such position by rotation of the clamping screw 15 by its handle 18. The stop pin 1| which extends downwardly from the hub will then be so positioned that when the shoulder 81 on the actuating rod engages the stop pin 1| the registry of the ports 4| and 42 will be so restricted, as illustrated in Fig. 6, as to throttle the escape of air from the lifting cylinder and cause the hammer to strike blows of uniform predetermined force indicated by the setting of the scale upon the hub. By manipulation of the handle 88 of the control rod the hammer may therefore be caused to strike a single blow or repeated blows of uniform predetermined force. hammer approaches the plane of impact on each descent the projection thereon will engage the cam and rotate the control rod in a clockwise direction so to position the ports 01' the valve 38 as to supply air under pressure to the lifting cylinder to raise the hammer.

'By reason of engagement of the plunger head 84 of the handle 88 with the flat surface 83 of the collar 8| the automatic rotation of the control rod 49 will merely force the plunger from engagement with the fiat surface 83 to engagement with the cylindrical surface of the collar and therefore will not cause any substantial shock to the hand of the operator while grasping the handle 88.

Upon each upward movement of the hammer the collar 28 on the piston H of the lifting cylinder will engage the tubular piston rod 2| of the bufier piston I9 and will cushion and arrest the upward movement of the hammer by re- As the sistance of the air pressure in the lifting cylinder and the bufi'er cylinder, as above described.

-When it is desired to stop the hammer the operator will release the pressure on the handle I00 of the 'rod 96 when the hammer approaches the upper limit of its movement and the spring 99 will thereupon swing the latch 98 beneath the lower face or a shoulder of the hammer. If the handle 1-00 is releasedat such time during the upward movement of the hammer that the latch may not engage the hammer the abutment rod 93' will :be positionedby-the spring 99 in the path of the hammer so that the hammer .die will be prevented from engaging and. injuring the. anvil die :or the work thereon, or the hands of the operator.. I I

By reason. of the communication of the branch 25 ofthe conduit 23 with the lower portion of the lifting cylinder, as above described, accumulation of excessive oil in the lower portion of the lifting cylinder is discharged by the exhaust of air from thecylinder. I I l By reason of the universal jointconnection between'thecontrol rod 49 and the valve 36 wear of the valve 35 and its bearings is practicallyeliminated. H

Itwilltherefore be obvious that by the present invention a drop hammer of simple construction and maximum longevity is provided which may be so controlled as to produce a single-blow of full force or anydesired lesser force or repeated blows of full force or any desired predetermined lesser, force.

It will be understood that the particular, mech-Q anisms shown and described herein'are of an ilconnected to the hammer, a conduitin' said beam communicatingat one end withthe cylinder'and at its other end with the atmosphere, a. rotatable valvein said conduit having vpo rtsiadapted respectively' to. be positioned to admit air into the reciprocably mounted on said columns, and a cylinder mounted on said beam having a piston connected to the hammer, a conduit in said beam communicating at one end with the cylinder and at its other end with the atmosphere, avalve in said conduit having ports adapted respectively to be positioned to admit air into the cylinder or to permit escapeof air from the cylinder and the hammer to drop, and means for supplying air under pressure to said valve, the provision of valve actuating mechanism comprising 'a'rotat ablevertical rod connected to and in axial alinement with said valve and journaled at its lower end in said anvil, means rigid with the lower end of said rod having shoulders extending outwardly therefrom in different directions, a stop member rigid with said anvil positioned to engage one of said shoulders when the rod is rotated in a direc-' blows of the same predetermined force.

cylinder or to' permit, escape of} airfrom the cylinder and the hammer to dema means for:

supplying air under pressure to said valve, the

provision .of' valve actuating mechanism comprising a rotatable vertical rod connected to and iniaxialalinement withsaid valve, "and journaled I at i'tsflower end in said anvil, means rigid with the lower end of saidrod having shoulders ex tending outwardly therefromin difierent directions. a stop member rigid with said anvil po sition'ed to engage one of said shoulders when the rod is rotated in a direction-to positionthe valveports to admit air into the cylinderaand a stop; member adj ustably mounted on said anvil adapted to be positioned in the path of; the other shoulder 'so to limit the rotation of the rod as to cause the ports, of thejvalveso to restrict the escape of air from the cylinder as to cause therhammer to strike a blow of predetermined force. f' I f 12. a pneumatic drop hammer having an anvil. a frame mounted thereon having vertical columnsfor guiding the hammerconnected at their upperv end by an overhead, beam, a hammer 3. In a pneumatic drop hammer having an anvil, a frame mounted thereonhaving vertical columns for guiding the hammer connected at their upper end by an overhead beam,-a hammer reciprocably mo'untedon said columns, and a cylinder mounted on said beam having a-piston connected to'thehammer, a conduit-in said beam communicating atone end with-the cylinder and at its other end With'the atmosphere; a

valve in said conduit having ports adapted re-- spectively to be positioned to admit air into the cylinder or to permit escape of air from the cylinder and the hammer to drop, and means for supplying air under pressure to said valve, *the provision of. valveactuatingmechanismcomprislower end .of'said rod mounted: in said anvil, and having a stop extending upwardly therefrom,

means :fixedly secured to the lower end portion 7 of said irod engaging said :bearing member and having laterallyextending arm's one of whic'h adapted to engage said stop: when said .rod' .;is"

rotated to positionthe valve ports to admit air into the cylinder,i.a manually operable control member. rotatably mounted upon saidxrodhaving a downwardly extendinglstop adapted to :be

engaged by the other arm on'zsaid' rod to limit the rotativemovement of said rodinzthe opposite direction thereby to position the exhaust ports of saidvalve'so to restrict the-escape of. a'irfrom the cylinder to. cause the hammer :to strike a blow of, predetermined force, and' means for locking said control memberv in.;adjusted 13051,- tions to causethe hammer toystrike 'repeated'l blows of the same predetermined ,force. v 4. In a pneumati'c dropheimmerhavinga anvil, a diesupportingaanvil, 'airamermounted on said anvil having vertical columns for guiding v the hammer connected at theirupper ends'by an Overhead bee a me f ficismcablv mounted on said columns,,,a liftingrylinder mounted on said beam having apistonconnected;

cylindrical socket in the anvil, a vertical threeway valve rotatably mounted in said beam in axial alinement with the socket in said anvil and having inlet and exhaust ports adapted selectively to communicate with said conduit and to be positioned to supply air to the cylinder or to permit the exhaust of air therefrom, and means for supplying air under pressure to said valve, the provision of means for actuating said valve comprising a rod connected to said valve and extending into said socket having at its end a portion forming a journal, a bearing member therefor fixedly secured in said socket having an upwardly projecting stationary stop, a rotatably adjustable hub mounted in said socket having a complementary downwardly projecting stop, means fixedly secured to said rod between said bearing and said hub having shoulders extending therefrom in different predetermined directions, one of said shoulders being adapted upon rotationof the control rod in one direction to engage the fixed stop and thereby position the inlet ports of said valve to supply air to the cylinderand theother of which shoulders is adapted upon rotation of said rod in the opposite direction to engage the stop of the adjustable hub and so position the exhaust ports of the valve as to regulate the rate of exhaust of air from the cylinder andthereby control the force of blow of the hammer.

5.'In a pneumatic drop hammer having an anvil, a die-supporting anvil, a frame mounted on said anvil having vertical columns for guiding thehammer connected at their upper ends by an overhead beam, a hammer reciprocably mounted on said'columns, a lifting cylinder mounted on saidbeamhaving a piston connected to the hammer, av conduit in said beam communicating at one end with said cylinder and at its other end with the atmosphere, a vertical cylindrical socket inlthe anvil, a vertical three-way valve rotatably mounted in said beam in axial alinement with the socket in said anvil and having inlet and exhaust p rts adapted selectively to communicate with said conduit and to be positioned to supply air to thecylinder or to permit the exhaust of air therefrom, and means for supplying air under pressure, tosaid valve, the provision of means for actuating said valve comprising a rod connected to said valve and extending into said socket havingintproximity to its end an angular section terminating in a. conical end portion forming a journal, a bearing member therefor rotatably andladjustably mounted in said socket having a conical bearing for theend of said rod secured in said socket having an upwardly projecting stationary .stop pin, arotatably adjustable hub mounted in said socket having a complementary downwardly projecting stop pin, a collar mounted on: the angular section of ,said shaft having shoulders extending therefrom in different predetermined directions, one of said shoulders being adapted upon=rotation of the control rod in one direction to engage the fixed stop and thereby position the inlet ports of said valve to supply air .to the cylinder and-the other of which shoulders isadapted upon rotation of said rod in the oppositedirection to engage the stop of the adjustable'huband so position the exhaust ports of -the valve'asto regulate the rate of exhaust oi air-fromthe cylinder and thereby control the force of blow of the hammer. I

6; Ina pneumatic 'drop' hammer having an anviLa die-supportingianvil, a frame mounted on sa'id'base having'vertical columns for guiding the 12 hammer connected at their upper ends by an overhead beam, a hammer reciprocably mounted on said columns, a lifting cylinder mounted .on said beam having a piston connected to the hammer, a conduit in said beam communicatin at one end with said cylinder and at its other end with the atmosphere, a vertical cylindrical socket in the anvil, a vertical three-way valve rotatably mounted in said beam in axial alinement with the socket in said anvil and having inlet and exhaust ports adapted selectively to communicate with said conduit and to be positioned to supply air to the cylinder or to permit the exhaust of air therefrom, and means for supplying air'under pressure to said valve, the provision of means for actuating said valve comprising a rod connected to said valve and extending into said socket having at its end a portion forming a journal, a

bearing member therefor fixedly secured in said direction to engage the fixed stop and thereby position the inlet ports of said valve' to supply air to the cylinder and the other of which shoulders is adapted upon rotation of said rod in the opposite direction to engage the stop of the adjustable hub and so position the exhaust ports of the valve as to regulate the rate of exhaust of air from the cylinder and thereby control the force of blow of the hammer, an index member mounted in said anvil support radially opposite to the fixed stop member, a scale on said hub cooperating with said index member adapted upon rotation of said hub to indicate the position of the exhaust ports of the valve, and means for clamping the hub member in adjusted position as indicated by the scale to determine the ratelof exhaust of air from the cylinder and the predetermined force of repeated blows of the hammer.

'I. In a pneumatic drop hammer having an anvil, a frame mounted thereon having vertical columns for guiding the hammer connected at their upper end by an overhead beam, a hammer ,reciprocably mounted on said columns, and a cylinder mounted on said beam having a piston connected to the hammer, a conduit in said beam communicatingat' one end with the cylinder-and at its other end with the atmosphere, a rotatable valve in said-conduit having ports adapted re-' spectively to be positioned to admit air intothe cylinder or to permit escape'of air from the cyl"- inder and the hammer to drop, and meansfor' supplying air under pressureto said valve, the provision of valve actuating mechanism compri e ing a rotatable verticalcylindrical rod connected to andin axial alinement with said valve and journaled at its lower end in said anvil and having j n P mi y hereto a flat surface, cooperating means on said hammerand rod operable {when the hammer closely approaches the anvilautof matically to rotate the valve in apdirectionto admit air to the cylinder, an operating handl ei rotatably mounted on said rod having means releasably engaging said rod with sumcie'nt force to enable the rotation thereof adjustably to place the ports of the valve in predetermined exhaust position and to release such engagementwhen' the rod is automatically rotated in the oppositel direction by the dropping hammer,thereby'to avoid shock to the hand and arm of the operator.

8. In a pneumatic drop hammer having an anvil, a frame mounted thereon having vertical columns for guiding the hammer connected at their upper end by an overhead beam, a hammer reciprocably mounted on said columns, and a cylinder mounted on said beam having a piston connected to the hammer, a conduit in said beam communicating at one end with the cylinder and at its other end with the atmosphere, a rotatable valve in said conduit having ports adapted respectively to be positioned to admit air into the cylinder or to permit escape of air from the cylinder and the hammer to drop, and means for supplying air under pressure to said valve, the provision of valve actuating mechanism comprising a rotatable vertical cylindrical rod connected to and in axial alinement with said valve and journaled at its lower end in said anvil and having in proximity thereto cooperating means on said hammer and rod operable when the hammer closely approaches the anvil automatically to rotate the valve in a direction to admit air to the cylinder, an operating handle rotatably mounted on said rod having a spring pressed plunger mounted thereon and movable longitudinally thereof, a flat head engaging the flat surface on said rod operable to rotate the rod in a direction adjustably to place the ports of said valve in predetermined exhaust position and operable upon automatic rotation of the rod in the opposite direction by the dropping of the hammer to avoid shock to the hand and arm of the operator.

9. In a pneumatic drop hammer of that type having an anvil, a hammer-guiding frame with an overhead beam, vertically alined lifting and buffer cylinders on the beam, a piston for the lifting cylinder having a piston rod connected 14 to the hammer, and a piston for the buffer cylinder having a tubular stem slidably mounted on the piston rod, the provision of an annular plate mounted on the beam forming a common head for the lifting and buffer cylinders and provided with means for permitting air to pass from the lifting cylinder to the buffer cylinder, and a valve-controlled means for selectively supplying air under pressure to the liftin cylinder to raise the hammer and thence to the buffer cylinder to cushion and arrest the hammer at the upper limit of its movement.

10. In a pneumatic drop hammer the construction as defined in claim 9 in which the said annular plate has an upwardly extending inner wall narrowly spaced from the piston rod acting to secure the discharge of oil accumulated between the said inner wall and the internal periphery of the lifting cylinder when the air is exhausted from the lifting cylinder.

REGINALD P. FITZGERALD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,531,490 Macready et al Mar. 31, 1925 1,722,506 Sahlin July 30, 1929 1,924,545 Fitzgerald et a1. Aug. 29, 1933 2,218,684 Murray Oct. 22, 1940 2,220,036 Fitzgerald Oct. 29, 1940 2,220,037 Fitzgerald Oct. 29, 1940 2,250,449 Eppens July 29, 1941 2,263,680 Fitzgerald Nov. 25, 1941 2,403,582 Caudill July 9, 1946 2,409,254 Conzelman, Jr Oct. 15, 1946 2,449,401 Lindsey Sept. 14, 1948 

